CN111786360A - Adapter circuit - Google Patents
Adapter circuit Download PDFInfo
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- CN111786360A CN111786360A CN202010604163.6A CN202010604163A CN111786360A CN 111786360 A CN111786360 A CN 111786360A CN 202010604163 A CN202010604163 A CN 202010604163A CN 111786360 A CN111786360 A CN 111786360A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
- H02H7/055—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers for tapped transformers or tap-changing means thereof
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/025—Disconnection after limiting, e.g. when limiting is not sufficient or for facilitating disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/06—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using spark-gap arresters
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Abstract
The invention relates to a BES choking adapter transformer circuit, which is applied to a railway track circuit and comprises: a BES choke adapter transformer, a first end of the primary side is used for connecting a first steel rail, and a second end is used for connecting a second steel rail; and the surge protection device is connected with the secondary side of the BES choking adaptation transformer in parallel and is used for protecting the insulation of the secondary side when power frequency open-circuit overvoltage occurs on the secondary side of the BES choking adaptation transformer. The radio frequency identification reader comprises the carrier suppression circuit. The surge protection device is arranged in parallel with the secondary side of the BES choking adaptation transformer circuit, and is used for absorbing the surge generated by the open-circuit overvoltage of the secondary side of the BES choking adaptation transformer when the secondary side of the BES choking adaptation transformer is open-circuit, preventing the insulation breakdown of the coil of the secondary side of the BES choking adaptation transformer and avoiding the damage of the BES choking adaptation transformer.
Description
Technical Field
The invention relates to the technical field of rail transit, in particular to an adapter circuit.
Background
With the development of rail transit technology, high speed, heavy load and electrification are the current development trend. In electrified rail transit, a traction power supply system and a signal system form a circuit by connecting rails, so that once the traction power supply system fails, hidden danger is brought to the operation of the signal system, and the operation of a vehicle is further influenced. In order to combine the functions of the traction power supply system and the signal system, it is necessary to use BES choke transformers, which are used for circulating traction current and for transmitting and receiving track signals, and are the parts of the track circuit used for realizing strong and weak current combination, which is very important in the track circuit,
however, in the operation process, the BES choke transformer often has a secondary side coil insulation breakdown fault, and after the secondary side coil of the BES choke transformer is broken down, the electrical service signal cannot be normally transmitted and received, so that the track section covered by the BES choke transformer cannot be normally used, and train passing is affected.
Disclosure of Invention
In view of this, it is necessary to provide an adapter circuit capable of preventing insulation breakdown failure of the secondary side coil of the BES choke transformer.
An adapter circuit for use with a BES choke transformer of a railway track circuit, comprising:
an adapter for connecting in parallel with a secondary side of the BES choke transformer; the first end of the primary side of the BES choke transformer is used for being connected with a first steel rail, and the second end of the primary side of the BES choke transformer is used for being connected with a second steel rail;
and the surge protection device is connected with the adapter in parallel and is used for protecting the insulation of the secondary side when the power frequency open-circuit overvoltage occurs on the secondary side of the BES choke transformer.
In one embodiment, the surge protection device is a spark gap type surge protection device;
and the minimum power frequency through-current capacity of the spark gap of the surge protection device is determined according to the maximum power frequency short-circuit current of a contact network and the transformation ratio of the primary side and the secondary side of the BES choke transformer.
In one embodiment, the minimum spark gap breakdown voltage of the surge protection device is 2-2.5 times greater than the normal operating voltage of the secondary side of the BES choke transformer when the maximum unbalanced current is allowed, and is less than the power frequency withstand voltage level of the secondary side of the BES choke transformer.
In one embodiment, the spark gap maximum breakdown discharge voltage of the surge protection device is less than the power frequency withstand voltage level of the secondary side of the BES choke transformer.
In one embodiment, the rated withstand voltage of the spark gap of the surge protection device is greater than the normal working voltage of the secondary side of the BES choke transformer and less than the long-term power frequency withstand voltage of the secondary side of the BES choke transformer.
In one embodiment, the cross-sectional area of the connecting line of the surge protection device is determined according to the minimum power frequency current capacity of the spark gap of the surge protection device.
In one embodiment, the device further comprises a nonlinear resistor;
the nonlinear resistor is connected with the surge protection device in series and used for adjusting residual voltage at two ends of a spark gap of the surge protection device.
In one embodiment, the resistance value of the nonlinear resistor is determined according to the minimum power frequency current capacity of the surge protection device and the power frequency withstand voltage grade of the secondary side of the BES choke adapter transformer.
In one embodiment, the device further comprises a tripping device;
the tripping device is connected with the surge protection device in series.
In one embodiment, the device further comprises a trip indicator;
the tripping indicator is connected with the tripping device in series and used for sending out a prompt signal, and the prompt signal is used for displaying the current state of the tripping device.
According to the BES choking adaptation transformer circuit, the surge protection device is arranged to be connected with the secondary side of the BES choking adaptation transformer circuit in parallel, and when the secondary side of the BES choking adaptation transformer is opened, the surge generated by the secondary side open circuit overvoltage of the BES choking adaptation transformer is absorbed, the insulation breakdown of the secondary side coil of the BES choking adaptation transformer is prevented, and the damage of the BES choking adaptation transformer is avoided.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a choke adapter transformer in one embodiment;
fig. 2 is a schematic structural diagram of a choke adapter transformer circuit in one embodiment.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, the first terminal may be referred to as a second terminal, and similarly, the second terminal may be referred to as a first terminal, without departing from the scope of the present application. Both the first terminal and the second terminal are coil terminals of a BES choke adaptation transformer, but they are not the same terminal.
It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.
BES choke transformers are abbreviated as choke flows, wherein B in the BES type choke adapter transformer represents a transformer, E represents choke, and S represents an adding adapter. As shown in fig. 1, the BES choke transformer is configured with an adapter which, in one embodiment, includes a 50Hz series resonant circuit and a resonant capacitor C2, the 50Hz series resonant circuit being connected in parallel with the resonant capacitor C2; the 50Hz series resonant circuit comprises an inductance L1 and a capacitance C1. The 50Hz series resonant circuit generates series resonance when the power frequency is 50Hz, and the 50Hz series resonant circuit presents low impedance; for the track circuit carrier frequency signal, the resonance capacitor C2 and the equivalent inductive reactance of the secondary side of the transformer generate parallel resonance to present high impedance. Because the adapter has limited current capacity through power frequency, an additional overcurrent protection device is generally arranged in series with the adapter, such as the fuse RD arranged in fig. 1. In some embodiments, an air switch may be used in place of fuse RD, and when the 50Hz line current is greater than the setting current of the air switch, the air switch trips to disconnect the adapter from terminal 12.
The inventor of the invention has found that when the current of the secondary side coil of the BES choke transformer exceeds the maximum passing power frequency current of the fuse RD, the fuse RD is fused, the adapter is disconnected, that is, the secondary side coil of the BES choke transformer is opened, and the voltage of the secondary side coil may exceed the insulation withstand voltage at the moment, so that the secondary side coil is subjected to insulation breakdown.
Taking the BES 2-1000 BES choke transformer as an example, the BES choke transformer has a secondary coil terminal 4 and a terminal 12 connected to two ends of the adapter respectively, and has a 50Hz loop impedance of less than 22.5 Ω, and a primary 50Hz equivalent impedance of less than 0.025 Ω. The setting value of the fuse RD is 5A, that is, the maximum line frequency current flowing from the primary coil 1 terminal to the 3 terminals is 150A. At this time, the maximum voltage of the primary coil was 3.75V, and the maximum voltage of the secondary coil was 112.5V. When the fuse RD is fused, the adapter loop of the secondary side coil is disconnected, so that the secondary side coil is opened. At this time, the impedance of the primary coil jumps to 0.6 Ω, the voltage jumps to 90V, and the voltage between the terminals 4 and 12 of the secondary coil jumps to 2700V. The normal 50Hz withstand voltage standard of the secondary side coil of the BES choke transformer is 2000V, so after the secondary side coil is opened, the voltage of the secondary side coil can exceed the level of the insulation withstand voltage, the insulation breakdown of the secondary coil can be caused, and the BES choke transformer is damaged.
When the secondary side coil of the BES choke transformer is opened, the voltage difference between the primary side coil and the secondary side coil is 30 times, the voltage borne by the primary side coil is lower, and the damage possibility is lower, in the embodiment, the primary side coil of the BES choke transformer is only 90V after jumping, the allowed voltage difference in the relevant regulations of a railway track circuit also reaches 50V, the difference value between the primary side coil and the secondary side coil is smaller, a surge protection device SPD is not suitable for being adopted, and because a signal loop exists in the circuit, a parallel capacitor is not suitable for carrying out surge protection, otherwise, signals cannot be normally sent and received, and therefore the secondary side coil is mainly protected. Because the secondary side coil has an adapter, surge protection cannot be performed using capacitive or inductive devices in order to avoid interference with the operation of the secondary side coil. When the secondary side coil generates open circuit overvoltage, larger power frequency current passes through, so that the piezoresistor with smaller current capacity cannot be used.
Based on this, in one embodiment, there is provided an adapter circuit for use in a BES choke transformer of a railway track circuit, comprising:
an adapter for connecting in parallel with the secondary side of the BES choke transformer; the first end of the primary side of the BES choke transformer is used for being connected with a first steel rail, and the second end of the primary side of the BES choke transformer is used for being connected with a second steel rail;
and the surge protection device SPD is connected with the adapter in parallel and is used for protecting the insulation of the secondary side when power frequency open-circuit overvoltage occurs on the secondary side of the BES choke transformer.
The first end of the primary side refers to a terminal of the primary-side coil that is located at the head end of the coil and is not connected to the rest of the coils in the primary-side coil, and the second end refers to a terminal of the primary-side coil that is located at the tail end of the coil and is not connected to the rest of the coils in the primary-side coil. If the primary side coil has only one set of coils, the first end and the second end are two terminals of the coil, respectively, and if there are multiple sets of coils in the primary side coil, for example, the BES choke transformer shown in fig. 2 includes two sets of coils on the primary side, the first end may be a 1 terminal, and the second end may be a 3 terminal; or the first end is a 3-terminal and the second end is a 1-terminal. The first steel rail and the second steel rail are two steel rails on the rail respectively. The BES choke transformer is connected with the first steel rail through the first end of the primary side, and the second end of the primary side is connected with the second steel rail, so that the BES choke transformer is connected into a railway track circuit.
Surge protection devices SPD, also called lightning protectors, are electronic devices that provide safety protection for various electronic devices, instruments and communication lines, and are generally used to protect surges that cause instantaneous overvoltage due to the influence of indirect lightning and direct lightning. The surge protection device SPD is connected with the secondary side of the BES choke transformer in parallel, and when the power frequency open-circuit overvoltage is sent to the secondary side of the BES choke transformer, the insulation breakdown of the overlarge current and voltage on the secondary side of the BES choke transformer is prevented through shunting, voltage limiting or discharging, so that the BES choke transformer is prevented from being damaged.
The adapter circuit is connected with the secondary side of the BES choke transformer circuit in parallel through the surge protection device, and is used for absorbing surge generated by open-circuit overvoltage of the secondary side of the BES choke transformer when the secondary side of the BES choke transformer is open-circuit, preventing insulation breakdown of a coil of the secondary side of the BES choke transformer, and avoiding damage of the BES choke transformer.
Since the surge protection device is generally used for protecting surges which cause instantaneous overvoltage due to indirect lightning and direct lightning, the surge protection device is applied to an adapter circuit of the BES choke transformer, and the existing mode cannot be directly adopted for selecting parameters, and needs to be determined by combining the characteristics of the BES choke transformer.
In one embodiment, the surge protection device SPD is a spark gap type surge protection device SPD;
the minimum power frequency through-current capacity of the SPD spark gap of the surge protection device is determined according to the maximum power frequency short-circuit current of a contact network and the transformation ratio of the primary side and the secondary side of the BES choke transformer.
When the secondary side coil generates open-circuit overvoltage, larger power frequency current flows through, and the spark gap type surge protection device SPD has higher current capacity and can bear the power frequency current when the secondary side coil is open-circuit overvoltage. In some embodiments, the minimum power frequency current capacity of the surge protection device SPD spark gap is embodied as a 0.3 second current carrying capacity. In one embodiment, the surge protection device SPD may be an open gap type or a closed gap type surge protection device SPD. The open gap type working principle is based on an arc discharge technology, and when the voltage between electrodes reaches a certain degree, air arcs are broken down to perform creepage on the electrodes. The closed gap type is a multilayer graphite gap surge protection device SPD, the surge protection device SPD mainly utilizes the continuous discharge of the multilayer gaps, and the discharge gaps of all layers are mutually insulated.
In other embodiments, if the requirements on the current capacity of the surge protection device SPD are relatively low, other types of surge protection devices may be selected, such as discharge tube type surge protection devices, varistor type surge protection devices, diode-suppressor type surge protection devices, combination type surge protection devices, or silicon carbide type surge protection devices.
The discharge tube type surge protection device includes an open discharge tube type and a closed discharge tube type, wherein the open discharge tube type is substantially the same as the open gap type surge protection device and belongs to an air discharger, but the open discharge tube type surge protection device has lower current capacity than the spark gap type surge protection device. The closed discharge tube type surge protection device mainly comprises a closed gas discharge tube, the closed gas discharge tube is also called an inert gas discharge tube, inert gas is filled in the closed gas discharge tube, the discharge mode is gas discharge, and the purpose of discharging current at one time is achieved by puncturing the gas. The voltage dependent resistor type surge protection device comprises a single-chip voltage dependent resistor type and a multi-chip voltage dependent resistor type, wherein the single-chip voltage dependent resistor type surge protection device utilizes the nonlinear characteristic of the voltage dependent resistor, zinc oxide is in a high resistance state when the voltage does not fluctuate, and the voltage dependent resistor is in a low resistance state rapidly when the voltage fluctuates to reach the starting voltage of the voltage dependent resistor, so that the voltage is limited within a certain range. The surge protection device with a plurality of piezoresistors mainly solves the problem that the flow of a single piezoresistor is small. The suppression diode type surge protection device is mainly applied to signal lightning protection products such as networks and the like in a large quantity, and the working principle is based on PN junction reverse breakdown protection. The combined type surge protection device comprises a simple combined type and a complex combined type, wherein the typical structure of the simple combined type surge protection device is in an N-PE structure form, and compared with the surge protection device with a single structure, the surge protection device integrates the advantages of two different products, and the defect of a single device is reduced. The complex combined surge protection device fully exerts the advantages of various components, and generally uses a large number of piezoresistors and gas discharge tubes on the structure. The surge protection device with the structure generally has high current capacity and low residual voltage. The silicon carbide type surge protection device is mainly applied to high-voltage power lightning protection.
The surge protection device SPD is generally used for lightning protection overvoltage, so that it is not possible to select parameters according to the method for determining parameters of the general surge protection device SPD, which needs to be combined with the characteristics of the BES choke transformer and the working environment of the railway track circuit. In order to avoid that the surge protection device SPD influences the normal work of a railway track circuit, the minimum power frequency capacity of the surge protection device SPD needs to be determined according to the maximum power frequency short-circuit current of a contact network and the transformation ratio of a primary side and a secondary side of a BES choke transformer, wherein the contact network is a high-voltage transmission line which is erected along a reversed Y shape above a steel rail and used for a pantograph to take current in an electric railway. The overhead contact system is a main framework of the railway electrification engineering and is a special power transmission line which is erected along a railway line and supplies power to an electric locomotive. Specifically, the minimum power frequency capability I of the surge protection device SPD can be determined according to the following expression:
wherein, I0The maximum power frequency short circuit current of the contact network; and n is the transformation ratio of the primary side and the secondary side of the BES choke transformer. For example, suppose that the maximum power frequency short circuit current I of the overhead line system0The maximum value can reach 10000A, taking the transformation ratio n of the primary side and the secondary side of the BES choke transformer shown in FIG. 2 as 30 as an example, the minimum power frequency capability I of the surge protection device SPD is 333A.
In one embodiment, the minimum spark gap breakdown voltage of the surge protection device is 2 to 2.5 times greater than the normal secondary side operating voltage of the BES choke transformer when maximum imbalance current is allowed, and less than the line frequency withstand voltage rating of the BES choke transformer secondary side.
In order to ensure that the surge protection device SPD can work normally and does not malfunction, the minimum breakdown voltage of the spark gap of the surge protection device SPD needs to be greater than the working voltage of the secondary side of the BES choke transformer and less than the power frequency withstand voltage level of the secondary side of the BES choke transformer. If the working voltage of the secondary side coil under normal working is too close, malfunction is easily caused by voltage fluctuation, and if the working voltage is too close to the power frequency withstand voltage level, the protection performance is poor. In some embodiments, the minimum breakdown voltage of the spark gap of the surge protection device SPD may take the intermediate value between 2 to 2.5 times the normal secondary operating voltage of the BES choke transformer when the maximum unbalanced current is allowed and the power frequency withstand voltage rating, taking into account a certain protection margin. In some embodiments, 1.1 times the minimum breakdown voltage of the spark gap of the surge protection device SPD is approximately equal to the power frequency withstand voltage level of the secondary side of the BES choke transformer, i.e., the minimum breakdown voltage of the spark gap of the surge protection device SPD is less than 90% of the power frequency withstand voltage level of the secondary side of the choke transformer. For example, assuming that the overvoltage at the time of opening the secondary side coil is 1080V and the power-frequency withstand voltage class is 2000V, the minimum breakdown voltage of the spark gap of the surge protection device SPD may be selected in a range of 1600V to 1800V.
In one embodiment, the spark gap maximum breakdown discharge voltage of the surge protection device SPD is less than the power frequency withstand voltage level of the secondary side of the BES choke transformer.
If the maximum spark gap breakdown discharge voltage of the SPD exceeds the power frequency withstand voltage level of the secondary side of the BES choke transformer, the SPD cannot play a role in protection. When the voltage reaches the power frequency withstand voltage level of the secondary side of the BES choke transformer, the BES choke transformer may be damaged, but the spark gap of the surge protection device SPD is not protected by the breakdown discharge. Therefore, the spark gap maximum breakdown discharge voltage of the surge protection device SPD should be less than or equal to the power frequency withstand voltage level of the secondary side of the BES choke transformer, for example, when the power frequency withstand voltage level of the secondary side of the BES choke transformer is 2000V, the spark gap maximum breakdown discharge voltage of the surge protection device SPD should not be greater than 2000V.
In one embodiment, the rated withstand voltage of the spark gap of the surge protection device SPD is greater than the normal operating voltage of the BES choke transformer and less than the long-term power frequency withstand voltage of the BES choke transformer.
In order to avoid the insulation failure of the spark gap of the surge protection device SPD, the rated withstand voltage of the spark gap of the SPD is necessarily larger than the voltage of the secondary side of the BES choke transformer for normal operation, and meanwhile, in order to ensure the reliability of the SPD, the rated withstand voltage of the spark gap of the SPD is required to be smaller than the long-term power frequency withstand voltage of the secondary side of the BES choke transformer. In one embodiment, the rated withstand voltage of the SPD spark gap of the surge protection device may be 2 to 2.5 times the normal operating voltage of the secondary winding of the BES choke transformer, taking into account a certain margin to avoid damage due to voltage fluctuations. For example, assuming that the normal operating voltage of the secondary winding of the BES choke transformer is 112.5V and the long-term power frequency withstand voltage is 700V or higher, the rated withstand voltage of the SPD spark gap of the surge protection device may be selected from 225V to 700V or 282V to 700V.
In one embodiment, the cross-sectional area of the connecting wire of the surge protection device SPD is determined according to the minimum power frequency current capacity of a spark gap of the surge protection device SPD.
Because surge protection device SPD needs to realize surge protection when BES choke transformer secondary side coil opens the way and overvoltage, if surge protection device SPD's resistance of connecting wire can't satisfy surge protection device SPD's operational need, can't realize surge protection, therefore need confirm according to surge protection device SPD's minimum power frequency discharge current capacity of spark gap, the sectional area is one of the parameter that influences conductor resistance, because in the railway track circuit, generally all use copper conductor as the connecting wire, consequently confirm the sectional area and can confirm the resistance of connecting wire, namely calculate the resistance of connecting wire according to surge ABOVU lake device spark gap's minimum power frequency discharge current capacity, can confirm the sectional area of connecting wire according to the law of resistance, and then select the connecting wire that accords with the requirement. In one embodiment, the cross-sectional area S of the connecting line is determined according to the following expressionj：
Wherein: i isgThe maximum short-circuit current of the secondary side of the choke transformer is equal to the maximum unbalanced current of the primary side divided by the transformation ratio of the choke transformer, for example, the maximum unbalanced current is 900A, and the transformation ratio of the choke transformer is 1: 30, the secondary side maximum current is 900/30 ═ 30A; j is the maximum allowable current density of the conductor material, the copper wire is usually 5A/mm2。
In one embodiment, the device further comprises a nonlinear resistor;
the nonlinear resistor is connected in series with the surge protection device SPD and used for adjusting residual voltage at two ends of a spark gap of the surge protection device SPD.
The nonlinear resistor is a resistor with characteristics which can be represented by a volt-ampere characteristic curve, and the nonlinear resistor does not follow ohm's law when conducting. Non-linearity refers to the fact that under certain conditions, the resistance of a resistor changes sharply.
The residual voltage of the surge protection device SPD refers to the peak voltage of a designated end of the surge protection device SPD when discharge current flows, namely when lightning discharge current passes through the surge protection device SPD, the voltage appearing between terminals of the surge protection device SPD, and the maximum residual voltage value appearing under the action of different currents is the limiting voltage of the surge protection device SPD. The surge protection device SPD is not used for lightning protection in the present invention, and therefore, in the present invention, residual voltage can also be understood as a peak voltage appearing between terminals of the surge protection device SPD when a discharge current generated when the secondary side of the BES choke transformer is open-circuited and overvoltage passes through the surge protection device SPD. The lower the residual voltage of the surge protection device SPD is, the lower the voltage that the secondary side coil bears when the open-circuit overvoltage of the secondary side of the BES choke transformer occurs, and the lower the risk that the secondary side coil is subjected to insulation breakdown. The nonlinear resistor is connected with the surge protection device SPD in series, and by using the characteristic of the nonlinear resistor, when the secondary side open-circuit overvoltage of the BES choke transformer occurs, the resistance of the nonlinear resistor is suddenly increased, so that voltage division is realized, partial residual voltage of the surge protection device SPD is consumed, and the reliability of the surge protection device SPD is improved.
In one embodiment, the resistance value of the nonlinear resistor is determined according to the minimum power frequency current capacity of the surge protection device SPD and the power frequency withstand voltage grade of the secondary side of the BES choke transformer.
In order to ensure that the nonlinear resistor can adjust residual voltage at two ends of a spark gap of an SPD (surge protection device), the power frequency same-current capability of the nonlinear resistor must be greater than the minimum power frequency current capability I of the spark gap of the SPD, so that the resistance value of the nonlinear resistor can be determined according to the following expression:
wherein R is0Is the resistance of the nonlinear resistor; v0And the power frequency withstand voltage grade of the secondary side of the BES choke transformer is obtained.
In one embodiment, the device further comprises a tripping device;
the tripping device is connected in series with the surge protection device SPD.
The tripping device has the function that when the SPD of the surge protection device fails, the tripping device can quickly cut off a circuit, and prevent surge current from entering the circuit to damage devices in a railway track circuit.
The tripping device is in the form of overcurrent tripping device, undervoltage tripping device, shunt tripping device, etc. Overcurrent trip devices can also be divided into overload trip devices and short-circuit (electromagnetic) trip devices, and have long delay, short delay, and instantaneous time. Overcurrent trip devices are most commonly used. The action current setting value of the overcurrent tripping device can be fixed or adjustable, and a knob or an adjusting lever is usually utilized during adjustment. The electromagnetic overcurrent tripping device can be fixed or adjustable, while the electronic overcurrent tripping device is usually always adjustable. The current tripping device can be fixedly mounted or modularly mounted according to the mounting mode. The tripping device needs to ensure stable and reliable operation and is not subjected to the influence of vibration and external force to trip when being positioned at a switching-on position. The trip unit should also have sufficient mechanical strength and rigidity, low tripping force and power (the force and power necessary to trip), and short tripping time (the time interval from the tripping action of the tripped unit to the tripping stop). The trip device must therefore have a large damping force, a small movement path and a small movement mass.
In one embodiment, the device further comprises a trip indicator;
the tripping indicator is connected with the tripping device in series and used for sending out a prompt signal, and the prompt signal is used for displaying the current state of the tripping device.
Because the operation and maintenance personnel are difficult to directly observe and judge whether the tripping device is tripped or not, the operation and maintenance personnel are not beneficial to timely troubleshooting and detection, and the tripping indicator is arranged to be connected with the tripping device in series, different prompt signals can be output according to different states of the tripping device, so that the operation and maintenance personnel can judge whether the tripping device is tripped or not according to the prompt signals, and timely troubleshooting and detection are carried out when the tripping device is tripped. In one embodiment, the prompt signal may indicate different states of the trip device by different colors, for example, when the trip device is in an untripped state, the trip indicator displays a green signal; when the tripping device is in a tripping state, the tripping indicator displays a red signal. In one embodiment, the prompt signal may also be a sound signal, and when the trip device is in the non-trip state, no sound prompt is given; when the tripping device is in a tripping state, a sound prompt is sent out.
In one embodiment, the trip device is remotely connected to a control center, which is capable of remotely monitoring the status of the trip device.
In one embodiment, for example, a BES 2-1000 BES choke transformer is used to select a type of the surge protection device SPD, and the specific selection method includes:
(1) the minimum power frequency current capacity I of the surge protection device SPD spark gap for 0.3 second is calculated by the following formula:
wherein, I0The maximum power frequency short-circuit current of the contact network is obtained, and n is the transformation ratio of the primary side and the secondary side of the BES choke transformer; assuming that the maximum power frequency short-circuit current of a contact network of the traction power supply system is 10000A, and the transformation ratio n of a BES 2-1000 type BES choke transformer is 30, the minimum power frequency current capacity I of a surge protection device SPD spark gap for 0.3 second is 333A.
(2) The minimum breakdown voltage requirement of the selected spark gap is not less than 1600V and is less than 2000V of the power frequency withstand voltage grade of the secondary side of the BES choke transformer;
(3) the selected maximum breakdown discharge voltage requirement of the spark gap is not more than 2000V of the power frequency withstand voltage grade of the secondary side of the BES choke transformer;
(4) the rated withstand voltage of the selected spark gap is not less than 400V;
(5) the cross-sectional area of the SPD connecting wire of the surge protection device is not less than 2.5mm2The copper wire of (1).
(6) When the residual voltage of the surge protection device SPD is limited by adopting the nonlinear resistor, the power frequency current capacity of the nonlinear resistor for 0.3 second is required to be larger than the minimum power frequency current capacity I of the spark gap of the surge protection device SPD for 0.3 second to be 333A, and when the voltage at two ends is 2000V, the resistance value R is the power frequency withstand voltage grade0The following requirements are satisfied:
wherein R is0Is the resistance of the nonlinear resistor; v0And the power frequency withstand voltage grade of the secondary side of the BES choke transformer is obtained.
(7) When the tripping device and the tripping indicator are adopted to prevent the short circuit of the spark gap, the minimum power frequency current capacity I of the surge protection device SPD spark gap of which the action current of the tripping device is 1.05 times is 0.3 second, and the action time of the tripping device is more than or equal to 0.3 second. The trip indicator uses different color differences to distinguish between an untripped state and a tripped state, for example, a red signal indicates the tripped state and a green signal indicates the untripped state.
As shown in fig. 2, the terminals 1 and 3 of the BES choke transformer are connected to two rails of a track, respectively, the terminal 2 is used for connecting with the terminal 2 of another BES choke transformer, N represents the number of turns of the coil, and 8N is 8 turns. The coils corresponding to terminals 4, 5, 6, 7, 8, 9, 10, 11 and 12 are secondary side coils, wherein the coil connected to terminals 4 and 5 is a signal coil, and N also represents the number of turns. An adapter, model QSP6(K), is connected between terminal 4 and terminal 12 of the secondary coil.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. An adapter circuit for use with a BES choke transformer of a railway track circuit, comprising:
an adapter for connecting in parallel with a secondary side of the BES choke transformer; the first end of the primary side of the BES choke transformer is used for being connected with a first steel rail, and the second end of the primary side of the BES choke transformer is used for being connected with a second steel rail;
and the surge protection device is connected with the adapter in parallel and is used for protecting the insulation of the secondary side when the power frequency open-circuit overvoltage occurs on the secondary side of the BES choke transformer.
2. The adapter circuit of claim 1, wherein the surge protection device is a spark gap type surge protection device;
and the minimum power frequency through-current capacity of the spark gap of the surge protection device is determined according to the maximum power frequency short-circuit current of a contact network and the transformation ratio of the primary side and the secondary side of the BES choke transformer.
3. The adapter circuit of claim 2 wherein the minimum spark gap breakdown voltage of the surge protection device is between 2 and 2.5 times greater than the normal secondary operating voltage of the BES choke transformer when maximum unbalanced current is allowed and less than the line frequency withstand voltage rating of the BES choke transformer secondary side.
4. The adapter circuit of claim 2 wherein a spark gap maximum breakdown discharge voltage of said surge protection device is less than a power frequency withstand voltage level of a secondary side of said BES choke transformer.
5. The adapter circuit of claim 2 wherein the surge protection device has a spark gap rated withstand voltage that is greater than the BES choke transformer secondary side normal operating voltage and less than the BES choke transformer secondary side long term line frequency withstand voltage.
6. The adapter circuit of claim 2, wherein a cross-sectional area of a connection line of the surge protection device is determined based on a minimum power frequency current capacity of a spark gap of the surge protection device.
7. The adapter circuit according to any of claims 2 to 6, further comprising a non-linear resistor;
the nonlinear resistor is connected with the surge protection device in series and used for adjusting residual voltage at two ends of a spark gap of the surge protection device.
8. The adapter circuit of claim 7, wherein the resistance of the nonlinear resistor is determined based on a minimum power frequency current capability of the surge protection device and a power frequency withstand voltage rating of the secondary side of the BES choke adapter transformer.
9. The adapter circuit of any of claims 2 to 6, further comprising a trip device;
the tripping device is connected with the surge protection device in series.
10. The adapter circuit of claim 9, further comprising a trip indicator;
the tripping indicator is connected with the tripping device in series and used for sending out a prompt signal, and the prompt signal is used for displaying the current state of the tripping device.
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| CN202010604163.6A CN111786360A (en) | 2020-06-29 | 2020-06-29 | Adapter circuit |
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| CN202010604163.6A CN111786360A (en) | 2020-06-29 | 2020-06-29 | Adapter circuit |
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| EP3343757A1 (en) * | 2015-08-28 | 2018-07-04 | Kabushiki Kaisha Toshiba | Railway vehicle, and vehicle power conversion apparatus and method |
| CN207826263U (en) * | 2018-01-31 | 2018-09-07 | 上海亨钧科技股份有限公司 | A kind of contactless whole electronic computer signal interlocking 25HZ orbits controlling modules |
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| WO2011068044A1 (en) * | 2009-12-04 | 2011-06-09 | 三菱電機株式会社 | Voltage transformer |
| CN105449655A (en) * | 2014-09-03 | 2016-03-30 | 国网河南省电力公司平顶山供电公司 | Current transformer secondary open circuit protection method and device |
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